I have a cub cadet hd gt2542 with kolher motor when started run and idles good but as soon as you open to full power and or put under load the butterfly on the carb flutters and then the motor starts to backfire and wants to cut out. Have been through the whole fuel system and carb. put new fuel line, took carb apart and clean the needle valve and carb, put on new fuel pump and just has me in a dumbfounded state. have taken it to a couple of small engine repair shops but has come back in worse shape than when I took it there! at the end of my rope please help!!!:tongue::tongue: